This invention relates to improvements in connectors for towing cable or conduit or the like, i.e., for stringing cables from pole to pole, hauling cable through underground conduits, and more particularly to swivel connectors for use with power and telephone cable, and especially to xe2x80x9cdisconnectxe2x80x9d swivels whose components separate under excess loading to preserve the cable especially for use with fibre optic cable and for hauling conduit for cable through underground bore holes.
The swivel connector disclosed in U.S. Pat. No. 2,387,599 uses ball bearings travelling in a race defined by or secured to opposed male and female components to interconnect and support same for rotation in relation to each other which male and female components thereof are to be connected to a hauling line and a cable respectively.
Such swivel connector cannot be taken safely around a pulley or bullwheel under load.
The swivel connectors revealed by U.S. Pat. Nos. 5,494,367 and 5,529,421 provide in one embodiment a first swivel head which is attached to a swivel shaft secured within a hollow body by a locking nut which in turn is connected to a second swivel head. Tapered roller bearings support the swivel shaft for rotation in one setting and transmit tensile loading from the shaft to the hollow body.
A series of restrictive seals serve to block the passage of debris from the outside to the interior.
In another embodiment the first and second swivel heads are attached to an opposed pair of swivel shafts and likewise are provided with restrictive seals with the object of utilizing the capability of one swivel head should the other fail.
The swivel connectors of U.S. Pat. Nos. 5,594,367 and 5,529,421 cannot, under load, be safely taken around a pulley or bullwheel.
The breakaway swivel connector disclosed in U.S. Pat. No. 4,678,365 has a centre pin from which material has been removed centrally internally thereof to create a shear factor so as to limit the load applied to the cable in installing same on poles or in underground ducts.
The breakaway connector of U.S. Pat. No. 5,122,007 uses assorted mechanical pin-type breakaways to protect the cable from damage in similar circumstances.
Both aforementioned breakaway connectors require replacement parts to be reinstalled after each cable pull has been completed and the sheared pin parts removed.
Each of the latter breakaway type connectors may require as many as twenty five (25) differently calibrated pins, preferably colour coded for identification of the breaking tension for installation either in the work place or in the field of operation. Such an arrangement, however, gives rise to human error in the selection of the requisite pin for the particular pull.
The breakaway components of the aforementioned U.S. Pat. Nos. 4,687,365 and 5,122,007 have been designed to separate at plus or minus ten (10) percent of their rated break load. Those limits, however, are not always precise or finite in that machine shop operations and the mechanical functions performed are also subject to human error leading to possible failure of the cable pull.
Moreover, the latter mentioned swivel connectors likewise are not designed to be safely taken around pulleys or bullwheels under load.
Further, the swivel connectors of all aforementioned U.S. patents operate safely only if loaded in one direction. Hence if incorrectly connected by attaching the wrong end to the cable to be pulled the swivel will fail and the cable pull aborted.
Other downside aspects inherent in the aforementioned breakaway connectors are the necessary disassembly to replace the break pins and then reassembly. Those steps can prove to be very costly in a field situation because of down time, because of potential loss of parts and the increased labour costs for disassembling and reassembling.
One principal object of this invention is to provide an improved swivel connector which can be loaded in either direction, that is, the swivel connector serves its purpose either way; and will operate whether the pull exerted is applied through the hauling line or through the cable itself.
Such swivel connector can include a separation or xe2x80x9cdisconnectxe2x80x9d structure for limiting the pulling load.
Another principal object is to provide a swivel connector that can be taken safely around a pulley or bullwheel under load.
Still another principal object of this invention is to provide an improved separation or xe2x80x9cdisconnectxe2x80x9d structure for a connector of the category under consideration which compared to known structures greatly minimizes the likelihood of damage to power and telephone cable and particularly to fibre optic cable during a cable pull whether overhead from pole to pole or underground in PVC ducts or conduits, in vaults or otherwise and to conduit hauled through underground bore holes.
Still another object is to provide an improved xe2x80x9cdisconnectxe2x80x9d connector which is fully reusable in a subsequent cable pull without any dismantling or disassembly of the components thereof or the replacement of parts in the reassembly of same, whereby human error in selection of replacement parts and reinstallation is entirely eliminated.
Another object of this invention is to provide an improved swivel connector that can be more easily utilized in confined spaces such as in riser ducts in high rise buildings, and follow a shorter bend radius as compared to known swivel connectors particularly when used in underground PVC ducts with its sweeps and bends.
It is also a specific object to provide an improved swivel connector of the type in which the separation or xe2x80x9cdisconnectxe2x80x9d tension characteristics have a substantially increased range of from about 100 psi to 5,000 psi and beyond if so desired.
Other important objects are to provide connectors including swivel connectors for the uses outlined which require low maintenance, are economically manufactured, do not require special tools in maintaining operability and have an extended operating life by virtue of the improved structure of same.
Features of the Invention
One feature of this invention resides in providing selected bearings for a swivel connector structure in which the swivel shaft is supported by and rotates within a bearing combination, in one embodiment, of a three (3)-piece dual thrust needle bearing at one end and by a flanged Permaglide(trademark) bearing at the other end and in another embodiment the combination of Permaglide(trademark) washer bearing and three (3)-piece needle dual thrust bearing at one end and a roller bearing at the other end.
Both embodiments are suitably sealed preferably by a Buna-N-O ring against ingress of debris and to contain lubricant which bearing combinations and seal confer upon the preferred embodiments the capability to be pulled safely under load in either direction; and further by reason of such combination of bearings the longitudinal dimension of connectors can be reduced, greatly facilitating travel through circuitous passageways and also around sheaves, pulleys or bullwheels.
Another feature of this invention resides in providing an interconnection between opposed surfaces of mating male and female components of a connector in the form of a selection of a spring loaded resilient steel ball mounted within an elongated passageway in either mating component to seat lowermost against an annular lip so shaped as to project a portion of the resilient steel ball beyond the opposed surface thereof and into a circumferentially extending matching recess or groove formation presented by the opposed surface of the other mating component, which spring loading of the steel ball can be so calibrated as to be forced from such groove formation and out of its seat into the elongated passageway only when the tensile loading applied to the mating components exceeds the spring loading applied to the resilient steel ball.
As a consequence of that arrangement the swivel components will separate or xe2x80x9cdisconnectxe2x80x9d before the cable ruptures or is otherwise damaged.
When separation occurs no parts are destroyed. The steel ball forced from the groove formation into its passageway after separation is then restored to its seated disposition by the associated spring so that the mating components can simply be reconnected by exerting the required compression force to re-establish mating relation.
More particularly in one embodiment of the invention the elongated passageway with its seating lip extends outwardly to the exterior from the opposed surface of such mating component generally radially or at right angles. Where multiple spring loaded steel balls are to be utilized in such embodiment several spaced apart passageways with seating lips can be selectively arranged in opposed pairs or in equidistant separation so as to achieve greater control over the applied loading for releasably securing the components against separation.
It is also contemplated in accordance with the invention that in the case of such embodiment where multiple spring-loaded steel balls are utilized in one mating component several circumferentially extending groove formations in suitably spaced apart relation can be formed in the opposed surface of the other mating component which arrangement through selection of appropriate springs, balls and loading factors can be used to control separation of the components upon reaching their respective load limits.
Still more particularly another aspect of this invention resides in selecting a stainless steel helical spring element which will operate effectively within a confined space as in the elongated passageway mentioned, preferably a stainless steel wave spring and further, which can be calibrated in that setting through an appropriate ratchet dial set screw engagement so as to selectively finitely exert pressure over a range of between 100 psi to 5,000 psi or greater through the compression spring seat bearing upon the stainless steel ball.
Another feature of this invention resides in providing an alternative passageway configuration for housing the spring loaded stainless steel ball in the embraced or male mating component for presentation to the matching circumferential recess or groove formation of the embracing or female mating component which alternative passageway includes a first portion extending generally inwardly from an exposed end of the embraced or male mating component and generally parallel to the opposed surface thereof which first portion intersects with a second portion extending outwardly therefrom lowermost and angled so as to intersect with such opposed surface and terminating in the annular lip or seat.
With such alternative passageway so shaped a component of the force exerted by the set screw setting and wave spring is first transmitted from the spring seat to a first resilient stainless steel ball located lowermost in the first passageway portion which engages a second stainless steel ball located lowermost in the second angled portion and forces it into seating engagement with the annular lip and so establish a modified release level or disconnect limit for the mating components under tensile and other forces.
With this arrangement the length of the passageway can be increased without increasing the diameter of the part which allow for increasing the extent of the spring element and increased loading of the steel ball.
More particularly the forces to be exerted by the wave spring in the foregoing alternative setting utilizing two stainless steel balls against the second ball located lowermost in the second angled passageway are first applied to the first or inner ball located lowermost in the first parallel passageway portion which contacts and transmits the forces to the second ball occupying the angled portion and seated on the annular lip all through appropriate selection of dimensions for the passageway portions steel balls and wave spring element.
Another feature resides in providing the first portion of the aforesaid alternative passageway with a slightly increased diameter as compared to the diameter of the angled portion and providing steel balls of corresponding diameters with appropriate clearances.
It is also contemplated that the alternative passageway configuration be further modified to include at least two opposed angled portions lowermost leading from the first passageway portion and to opposed or spaced apart seating annular lips with the wave spring loading transmitted by the centrally located steel ball lowermost in the first parallel passageway portion to the two steel balls each occupying one of the angled passageway portions and seated against the opposed or spaced apart lips thereof to project beyond the bounding longitudinal surface thereof and into engagement with the opposed circumferential groove formation.
Still another feature resides in providing a unitary resilient steel ball and spring element so that placement of same within the cylindrically shaped passageway in certain embodiments is facilitated and the process of assembly streamlined.
Other features are to be found in the improved connectors, according to the invention, in that not only can the dimensions of the mating components be reduced through the selection of bearings and their dispositions as earlier mentioned but also through the simplification of the xe2x80x9cdisconnectxe2x80x9d structure while maintaining the requisite loading capabilities; which reduced dimensions confer greater flexibility and endurance when passed around sheaves or pulleys or bullwheels or where a cable is pulled through the convolutions of conduits in buildings or buried, all for greater economic benefit.
Further advantages arise out of simplification of the connector structure in the steps of manufacture and assembly in the workplace and in the field with the savings in time and effort promoting greater profitability.
These and other objects and features of the invention are apparent in the following description to be read in conjunction with the sheets of drawings illustrating the preferred embodiments.